In recent years, the popularity of three wheeled motorcycles or motorcycle trikes has greatly increased, resulting in the development of conversion kits that transform a conventional motorcycle into a trike. These kits allow users to enjoy the many benefits of conventional motorcycles without requiring the same level of riding skill or physical ability. A popular motorcycle trike consists of a frame similar to that of a motorcycle coupled to a motorcycle front suspension and single leading wheel in the front, and a pair of wheels in the rear mounted in a parallel, spaced apart fashion. The frame is attached to the front suspension at the neck. From the neck, numerous frame members attach to it and continue rearwardly over, around and under the engine and transmission, enclosing them in a cage-like fashion. This design requires the rider and passengers to sit in an elevated position over the engine and around the frame in the same seating position as a traditional motorcycle.
Conversion of a conventional motorcycle to a trike generally requires the purchase of a kit that replaces the rear section of the frame and suspension with two driving wheels mounted in a traditional swing-arm fashion. This, however, only allows the wheelbase to be lengthened marginally, if at all. The short wheel base, in turn, restricts the width allowed between the rear wheels, thus producing a very short and narrow trike that can be unstable at anything over moderate speeds. By producing a frame specifically designed for trikes, with a longer and wider wheelbase that accepts live or independent rear axles, these problems can be resolved.
The addition of a second rear wheel, increased vehicle weight, cargo, passenger and towing capabilities reduces the driving horsepower dramatically. To correct the problem automotive engines are often used, producing substantially higher outputs of horsepower and torque. This causes stress loads not seen on a conventional motorcycle conversion, thus threatening the structural integrity of the frame and the safety of the riders.
Increasing the overall weight, combined with the high seat height for the riders and passenger, creates a high center of gravity. This causes a negative effect on cornering and handling ability thus compromising safety of the riders. By lowering the power-train and seat height into the frame, better handling characteristics can be achieved. There is a need for a trike frame designed to support the increased weight and torque loads, thus allowing the engine and riders to sit in a lower position and producing a lower center of gravity. The frame should also be designed with a longer, wider wheelbase for increased stability in cornering and at higher speeds, thus improving the handling and safety of the riders.
Trikes powered with automobile engines sometimes require radiators. The most common design is the use of a single radiator mounted in the front or rear of the vehicle. Both can have major drawbacks. Mounting the radiator in front produces large amounts of heat transferred back on the engine and riders. Mounting the radiators in the rear causes insufficient air flow through the radiators, thus causing cooling problems. By mounting a pair of radiators in the middle of the body on either side of the driveline, cool air can be forced into openings in the body passing through the radiators, exiting out of the bottom, and continuing to the rear of the trike, thus eliminating the problem of overheating the engine or riders.
A common exhaust system approach for front engine trikes is to route the system along the outside of the trike body in an exposed manner. The problem with an exposed exhaust system is that the hot exhaust pipes can cause serious injury to riders mounting and dismounting the trike, and can also accidentally cause injury to passing or curious pedestrians who happen to contact the exhaust pipes while the trike is unattended.
Another common problem with trikes of the type disclosed herein is a very limited cargo capacity. Most trikes have cargo capacity which is the same as or perhaps marginally greater than that available on a conventional motorcycle. This lack of cargo space limits the utility of the trike to function as a true multi-passenger vehicle, particularly for longer road trips.
Motorcycle trikes of the type disclosed, using an automobile engine mounted in the front of the vehicle require an extended steering system to reach the rider positioned behind the engine. One prior art practice is to use extended handlebars or steering rods from the front suspension, which extend rearwardly over the engine to the rider behind the engine. This approach, however, can pose problems if a hood is incorporated into the body design.
A motorcycle trike body can be produced by either adding a body to a portion of an existing motorcycle using a conversion kit, or designed in its entirety for a specific application. A common type of trike consists of a frame with multiple brackets for various components attached to it, covered by a body. Most prior art trike bodies are made of fiberglass from molds for ease of reproduction. Significant advantages could be obtained by incorporating the components of the trike into the design of the fiberglass body, since this approach would significantly reduce fabricating costs and thus substantially lower the cost of production.